barn owl vs owl

barn owl and owl both are nouns.

Word	Noun	Adjective	Verb	Adverb
barn owl	Yes	No	No	No
owl	Yes	No	No	No

As nouns, owl is a hypernym of barn owl; that is, owl is a word with a broader meaning than barn owl:

barn owl: mottled buff and white owl often inhabiting barns and other structures; important in rodent control
owl: nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes

Other hypernyms of barn owl include bird of Minerva, bird of night, hooter.

barn owl (noun)	owl (noun)
mottled buff and white owl often inhabiting barns and other structures; important in rodent control	nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes